In the design of digital logic circuits, large scale integration techniques have brought about the construction of large numbers of components being fabricated on a single chip of silicon. In such circuitry, utilizing metal-oxide-semiconductor (MOS) techniques, random access memory devices as well as other semiconductor circuitry utilize numerous clock signals to provide a time base for such circuitry. Such clock signals are generated by oscillator circuits. Oscillator circuits find use in telecommunications integrated circuits, such as, for example, repertory dialers in which operation at low power and low voltage is essential.
A previously developed oscillator is shown in U.S. Pat. No. 4,205,279 issued to Beutler on May 27, 1980 and entitled "CMOS Low Current RC Oscillator". Such previously developed oscillators have not provided operating characteristics at sufficient low voltage and low power requirements. Additionally, such previously developed oscillators are sensitive to temperature and not completely independent of environmental temperatures.
A need has thus arisen for an RC oscillator for use in semiconductor circuitry which operates at low voltage and low power requirements. Further, a need has arisen for an RC oscillator that is less sensitive to temperature and supply voltage parameters. Additionally, a need has arisen for an RC oscillator that can be fabricated on a single CMOS semiconductor chip with improved reliability while being cost effective.